"Humanoid::ApplyDescription() can only be called by the backend server"?

I'm trying to make a statistics page for players when you click on their name in my custom player list; however, when I came to rendering their avatar with a ViewportFrame I'm getting the error "Humanoid::ApplyDescription() can only be called from the backend server" when I try to apply their appearance.

Error script:

local ReplicatedStorage = game:GetService("ReplicatedStorage");
local Players = game:GetService("Players");
local SelectedPlayer = script.Parent.Parent.SelectedPlayer;
local ViewportFrame = script.Parent;
local Title = script.Parent.Parent.TopBar.Title;

SelectedPlayer:GetPropertyChangedSignal("Value"):Connect(function()
    local ID = Players:GetUserIdFromNameAsync(SelectedPlayer.Value);
    local Appearance = Players:GetHumanoidDescriptionFromUserId(ID);
    Title.Text = "Player Info - "..SelectedPlayer.Value;
    ViewportFrame.AvatarViewport.Humanoid:ApplyDescription(Appearance); -- Error Line?
end);

I have no clue why this is happening and have no clue how to fix it. Help is appreciated!